In wedge-actuated collet chucks of this type known to the art, the wedge-shaped pieces engage base gripping jaws laterally by way of helical gears (German Published Application DAS 1 059 741), or are provided with a bolt head formed by wedge surfaces running in parallel, the former engaging the wedge socket on the back side of the base gripping jaw (German Patent DT-PS 2 139 718).
These known wedge-actuated collet chucks have the disadvantage that they do not permit rapid and simple change of the gripping jaws, a particularly desirable feature for numerically controlled machine tools in order to expand the working capacity of such machines by enabling them to accept special gripping jaws.
To eliminate this disadvantage, German Offenlegungsschrift DT-05 2 052 037 has shown a form of construction in which the wedge-shaped pieces and the wedge sockets are designed as wedge hooks engaging each other, whereby the wedge hooks forming the wedge-shaped pieces are attached to a drive piston rotating about the chuck axis, thereby making it possible to disengage the wedge-hook connection from the gripping jaws by rotating the drive piston in order to exchange the gripping jaws. Such chucks are, however, always of a special design which does not lend itself to forming the chuck as a hollow chuck, i.e. with a central passage for executing rod work, or the like.